Apple has provided NVM Express protocol as an update for its OS X 10.10.3 earlier this week, which promises to increase its SSD performance significantly. The NVMe stands for Non-Volatile Memory Express which is in fact, latest and potentially better than the AHCI (Advanced Host Controller Interface) that Apple was using until now in its systems. Though this update and tweak made by Apple was pretty quiet as its recent release of a new Photos app and support for Emoji attracted all the attention. It still couldn't be simply ignored.
Putting it simply, the NVMe defines an optimized command set for PCIe based SSDs (Peripheral Component Interconnect Express) which Apple has already upgraded to years back and hence, there's no need to customize the system's hardware in order to utilize NVMe. According to NVMe's website, "The NVM Express specification defines an optimized register interface, command set and feature set for PCI Express (PCIe)-based Solid-State Drives (SSDs). The goal of NVM Express is to unlock the potential of PCIe SSDs now and in the future, and standardize the PCIe SSD interface."
NVMe was built by a giant industry consortium including Intel and it is optimized for lower latency operations by a SSD whereas the older AHCI was built years back mainly for the HDDs. NVMe reduces latency by almost 50% when compared to AHCI, allowing in a speedier SSD at lower power consumption.Apple's new 12 inch Macbook with Retina display comes already with PCIe SSDs and will take full advantage of NVMe protocol to make its performance better than its predecessors. To check whether your Mac supports NVMe after update, goto 'Hardware' and click the 'NVMExpress', supported drives will be listed and if it prompts with a “doesn't contain any NVMExpress devices.” message, you will have to upgrade your Mac.